ICPC 2012 Jakarta 6044 - Unique Path

這題只能說 我覺得很難 而且難到靠北，靠班上的牛人想法AC了

//============================================================================
// Name        : 6044 - Unique Path.cpp
// Date : 2013/3/17 下午3:35:38
// Author : GCA
//============================================================================
#include <iostream>
#include <cstdio>
#include <cstring>
#include <algorithm>
#include <cmath>
#include <climits>
#include <vector>
#include <set>
#include <map>
#include <queue>
#include <cctype>
#include <utility>
using namespace std;
#ifdef ONLINE_JUDGE
#define ll "%lld"
#else
#define ll "%I64d"
#endif
typedef unsigned int uint;
typedef long long int Int;
#define Set(a,s) memset(a,s,sizeof(a))
#define Write(w) freopen(w,"w",stdout)
#define Read(r) freopen(r,"r",stdin)
#define Pln() printf("\n")
#define I_de(x,n)for(int i=0;i<n;i++)printf("%d ",x[i]);Pln()
#define De(x)printf(#x"%d\n",x)
#define For(i,x)for(int i=0;i<x;i++)
#define CON(x,y) x##y
#define Pmz(dp,nx,ny)for(int hty=0;hty<ny;hty++){for(int htx=0;htx<nx;htx++){\
    printf("%d ",dp[htx][hty]);}Pln();}
#define M 10011
#define PII pair<int,int>
#define PB push_back
#define oo INT_MAX
#define Set_oo 0x3f
#define Is_debug true
#define debug(...) if(Is_debug)printf("DEBUG: "),printf(__VA_ARGS__)
#define FOR(it,c) for(__typeof((c).begin()) it=(c).begin();it!=(c).end();it++)
#define eps 1e-6
bool xdy(double x,double y){return x>y+eps;}
bool xddy(double x,double y){return x>y-eps;}
bool xcy(double x,double y){return x<y-eps;}
bool xcdy(double x,double y){return x<y+eps;}
int min3(int x,int y,int z){
    int tmp=min(x,y);
    return min(tmp,z);
}
int max3(int x,int y,int z){
    int tmp=max(x,y);
    return max(tmp,z);
}
int dis[M],low[M],t;

int test;
int n,m;
bool isbridge[M][M];
int died[M];
vector<int> mz[M];
vector<int> SaveDie;

void dfs(int p,int i){
//    debug("run?");
    dis[i]=low[i]=++t;
    int child=0;
    FOR(it,mz[i]){
        int u=(*it);
        if(u!=p){
            if(dis[u]){
                low[i]=min(low[i],dis[u]);
            }
            else{
                child++;
                dfs(i,u);
                low[i]=min(low[i],low[u]);

                if(low[u]>dis[i]){
                    isbridge[i][u]=isbridge[u][i]=true;
//                    debug("%d %d is bridge\n",i,u);
                }

            }
        }
    }
}
//int q[M*M],front,rear;
int vis[M];
void bfs_die(int i){
    queue<int> q;
//    front=rear=0;
//    q[front++]=i;
    q.push(i);
    vis[i]=1;
    while(!q.empty()){
        int u=q.front();q.pop();
        FOR(it,mz[u]){
            int v=(*it);
            if(!vis[v]&&!isbridge[u][v]){
//                q[front++]=v;
                q.push(v);
                vis[v]=1;
                SaveDie.PB(v);
                SaveDie.PB(u);
            }
        }
    }
    FOR(it,SaveDie){
//        debug("Die %d\n",*it);
        died[*it]=1;
    }

}
int cnt;
void bfs(int i){
    queue<int> q;
    q.push(i);
    vis[i]=1;
    while(!q.empty()){
        int u=q.front();q.pop();
        FOR(it,mz[u]){
            int v=(*it);
            if(!vis[v]&&!died[v]){
                q.push(v);
                vis[v]=1;
                cnt++;
            }
        }
    }
//    debug("cnt %d\n",cnt);
}
inline int cn2(int n){
    return (n*(n-1))/2;
}
void solve(){
    Set(dis,0);
    Set(low,0);
    Set(died,0);
    Set(isbridge,0);
    t=0;
    for(int i=1;i<=n;i++){
        if(!dis[i])dfs(i,i);
    }
    for(int i=1;i<=n;i++){
        Set(vis,0);
        SaveDie.clear();
        if(!died[i])bfs_die(i);
    }
    Set(vis,0);
    int ans=0;
    for(int i=1;i<=n;i++){
        cnt=1;
        if(!died[i]){
            bfs(i);
            ans+=cn2(cnt);
        }
    }
    printf("%d\n",ans);

}
int main() {
    ios_base::sync_with_stdio(0);
    int ff=0;
    scanf("%d",&test);
    while(test--){
        scanf("%d%d",&n,&m);
        for(int i=0;i<m;i++){
            int u,v;
            scanf("%d%d",&u,&v);
            mz[u].PB(v);
            mz[v].PB(u);
        }
        printf("Case #%d: ",++ff);
        solve();
        for(int i=0;i<=n+1;i++){
            mz[i].clear();
        }
    }


}